You can now enchant weapons that are Fabled class or higher to +15. Of
course, being higher in level, you’ll need a good bit of luck and kinah to
accomplish it. To help make this task more achievable, Enchant Assisting
Materials (Supplements) have been introduced in the 1.9
update. Supplements increase the success rate of enchanting and
socketing and can be purchased from a Potion Supplies or Remodeled Items
Vendor.

If you attempt to enchant an item or socket a manastone while Supplements are
in your Inventory, a Supplements window will appear.